With the progress of small-size, high-speed and lightweight electronic devices such as cellular phones and personal computers, the capacitor used for these electronic devices is demanded to have a smaller size, a larger capacitance and a lower ESR.
A solid electrolytic capacitor is composed of a conductor (anode body) as one electrode, a dielectric layer formed on the surface of the electrode, and a counter electrode provided thereon (semiconductor layer).
As one such example, it is possible to produce a sintered body from powder mainly comprising tungsten and to produce a solid electrolytic capacitor using the sintered body as an anode, and a small-size and high-capacitance capacitor, which is inexpensive as well, can be obtained. The capacitor can be installed in electronic devices as a microcircuit component.
However, like a conventional solid electrolytic capacitor, the above-mentioned capacitor emits smoke in some cases when the solid electrolytic capacitor shorts out for some external factors and a large current passes through. For these reasons, there has been a demand for a solid electrolytic capacitor which is hard to emit smoke or ignite even if it shorts out and a larger circuit current passes through.
As such a solid electrolytic capacitor which is hard to emit smoke or ignite, a capacitor using niobium monoxide as an anode body has been proposed (International publication WO 2007/020464; Patent Document 1). However, an anode body made of niobium monoxide has a low CV value per volume and it has been difficult to obtain a smaller-size and higher-capacitance capacitor compared to a conventional solid electrolytic capacitor such as a tantalum solid electrolytic capacitor.